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Biostratigraphy of the Upper Cretaceous of Romania

1994; Elsevier BV; Volume: 15; Issue: 1 Linguagem: Inglês

10.1006/cres.1994.1003

1095-998X

J. Ion, L. Szasz,

Evolution and Paleontology Studies

This paper is a synthesis of published and new ammonite, inoceramid and planktonic foraminiferal biostratigraphic data obtained by the authors from the Upper Cretaceous rocks of the East and South Carpathians, especially from the Median Dacides tectonic units, as well as the Babadag basin of North Dobrogea, Romania. An integrated biostratigraphical scheme, using the above three fossil groups, is presented for the Cenomanian to Coniacian interval. A few new ammonite zones are established for the Cenomanian to Coniacian in Romania, and in the Turonian to Coniacian several association and inoceramid association zones are identified. The planktonic foraminiferal zones established in Romania contain few zones of the new standard scales proposed for the Tethyan realm. Most zones and subzones have been established in diverse Tethyan regions or in Romania, and two planktonic foraminiferal subzones are introduced in this paper. The first appearances of foraminifers such as Rotalipora cushmani, R. turonica, Dicarinella concavata, D. asymetrica, Contusotruncana fornicata, Globotruncana aegyptiaca, G. falsostuarti and Globotruncanita stuarti as defined in Romania, differ from the standard scale; the level at which Rotalipora sensu lato and Helvetoglobotruncana helvetica disappear is undefined. The association with Inoceramus schloenbachi belongs entirely within the lower Coniacian, and the presence of Barroisiceras haberfellneri, Forresteria petrocoriensis and Maginotruncana tarfayensis indicates the base of the lower Coniacian. The Coniacian succession in the Caugagia-Baia region of North Dobrogea is identified as a possible hypostratotype. Santonian to Maastrichtian strata contain few and poorly studied macrofossils, and a zonation using planktonic foraminifers only is possible.